Heat Exchanger

ABSTRACT

A heat exchanger comprising an outer jacket ( 9 ) with an inner set of vertical pipe elements ( 1 ) fastened at their opposing ends in upper and lower sieve walls ( 2, 3 ), and having a gas combustion chamber ( 4 ) located above the upper sieve wall, as well as partitions ( 5, 6, 7 ) mounted crosswise of the pipe elements. The partitions have openings for the pipe elements. The heat exchanger is also provided with liquid, gas and exhaust fumes inlet and outlet stub pipes. The outer jacket is conically shape with its diameter increasing upwards. An upper sieve wall ( 2 ), is essentially flat as viewed from the side, while an upper partition ( 5 ) situated below the wall, is shaped as a cone with its vertex pointing down. The upper partition ( 5 ) has a central opening ( 8 ) in its central region and an outer diameter corresponding to a diameter of the outer jacket ( 9 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of previously filedU.S. Ser. No. 12/957,760, filed Dec. 1, 2010, entitled “Heat Exchanger”,by the same inventor. This case also claims priority from an earlierfiled Polish application, Serial No. P392560, filed Oct. 1, 2010,entitled “Heat Exchanger” by the same inventor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to heat exchangers of the typebelonging to the group of pipe exchangers designed to exchange heatbetween a gas and a liquid and, more particularly, to such heatexchangers designed to be used in heat engineering, especially indomestic central heating systems.

2. Description of the Prior Art

Many kinds of pipe heat exchangers are known having different structuresdepending on their particular environment of use, the fluids circulatingin a heat exchange system as well as special demands and needs. A systemof pipe elements in which a hot gas or liquid flow is a common featureof pipe heat exchangers, said elements being fastened between two sievewalls and situated in a chamber enclosed in an outer jacket in whichheated water or gas circulates. In the case of heat exchangers fordomestic central heating systems, in which heat is created by using gasas a fuel, such exchangers are known which are provided with acombustion chamber situated above the upper sieve wall and also having awater inlet as well as a water outlet stub pipes, a gas inlet stub pipeand an exhaust stub pipe. A set of pipe elements is positionedvertically in such exchangers. Heat exchangers are also known for use inthe heat power engineering field. Such exchangers are designated ascondensers or liquefiers and are built-up of many sets of pipe elementslocated in a chamber confined with an outer jacket. Pipes of saidexchangers are fastened between perforated bottom elements with waterchambers situated there between. Such exchangers are used, for example,where water working as an agent for cooling steam provided from outletsof turbines into a chamber closing said pipes is introduced into saidpipes. In pipe exchangers of different kinds such as these, and in orderto increase the heat exchange efficiency, pipe elements are used ofdifferent shapes and inner areas, as well as additional elements ofdifferent kinds, such as partitions, additional pipes and the like.

From the Polish patent specification No 1 8 6723 a pipe liquid-to-gasheat exchanger is known in which hot gas is introduced into a chamberclosed by an outer jacket, said gas being cooled when flowing aroundpipes fastened between flat sieve bottoms. A cooling agent flows throughthese pipes, said agent being delivered and carried out through stubpipes situated in a cover of the sieve bottom. Liquefied gas is drainedoff an outlet stub pipe situated in an outer jacket surrounding the heatexchange chamber. Additional perforated pipes are also located in thischamber, whereas end parts of said pipes are going through the sievebottom, and are connected with a collecting pipe which is connected to avapors off-take pipe. The perforated pipes are used to suck out air froma gas space in the exchanger and to lead it out from the exchanger.Partitions are also located in the exchanger chamber, said partitionsbeing situated crosswise in relation to pipe elements.

Form the published international patent application No. WO2008/131616, aheat exchanger is also known comprising an outer cylindrical jackethaving inlet and outlet stub pipes with a packet of pipe elementslocated in said jacket, said pipe elements going through a spiralpartition and being connected to sieve walls shaped as flat discsclosely forming to the cylindrical outer jacket. These tie rods are fromone side fastened in a sieve wall, and their other ends are fastened inthe spiral partition. The tie rods are divided into segments providedwith distance pipes. Such an exchanger may also be provided withadditional pipes going through the spiral partition without beingfastened in the sieve walls, upgrading stiffness, protecting againstdeformations and making it easier to match openings in the spiralpartition to the exchanger pipes. The construction of this spiralpartition is disclosed in detail and in the cited specification.

From the published international patent application no WO2009/078577 aboiler is known comprising a cylindrical casing, a vertical liquid-gasexchanger, a burner located in a combustion chamber of said exchanger,as well as an inlet and outlet of the water being heated, an exhaust gasoutlet, a gas inlet and an instrumentation enabling air supply andmaking suitable air-gas mixture, and moreover provided with a controldevice. This embodiment of a heat exchanger has a set of pipe elementsrectangular in a section, said pipe elements being regularly distributedinside an outer jacket forming a chamber through which the heated waterflows. Upper ends of these pipes are fastened in a flat upper sievewall, above which there is located a combustion chamber, their lowerends are through a flat lower sieve wall and a combustion gasesrecycling chamber connected to a combustion gases outlet channel.

Flat partitions, shaped as perforated discs, are located in the waterchamber, said pipe elements being run through said discs. Theseseparating partitions improves the heat exchange characteristics becausethey disturb the water circulation. The partitions are located crosswiseto the pipe elements, their diameter is smaller than the inner diameterof the jacket of the exchanger in order to create between the partitionsand the jacket slots through which water flows. The partitions aresituated crosswise to the pipe elements, their diameter installer thanthe inner diameter of the jacket of the exchanger so that water flowslots are created. An impact of the width of said slots onto the watercirculation and the water pressure acting onto partitions is discussedin the previously cited specification.

The solution described in the previously cited reference proposes toprovide said partitions with circulation pipes protecting against agreater water pressure acting onto said partitions, the upper ends ofsaid pipes being fastened in the highest partition, and the lower endsbeing fastened in the lowest partition. There is also shown analternative in which walls of the pipe elements are situated in adistance from the edges of openings in those partitions through whichthey are going, which design makes the water flow disturbances greater,thereby improving the heat exchange efficiency. The described boiler isprovided with an additional independent water circuit through spiralpipes disposed in the water chamber around the combustion chamber.

Despite the various advances described in the above prior artreferences, their continues to exist a need for further improvements inthe art of heat exchangers of the type under consideration.

SUMMARY OF THE INVENTION

A heat exchanger according to the invention is described having an outerjacket with a set of vertical pipe elements fastened at their ends, ateach of the opposite extents thereof in sieve walls, and having a gascombustion chamber located above an upper sieve wall, as well aspartitions mounted crosswise to the pipe elements. The partitions haveopenings for the pipe elements. The heat exchanger is also provided withliquid, gas and exhaust fumes inlet and outlet stub pipes, characterizedin that said outer jacket is conically shaped with its diameterincreasing in an upwards direction. In one version of the invention, anupper sieve wall as well as an upper partition lying below said wall areshaped as cones with their vertexes pointing down, said upper partitionhaving a central opening in its central part and its outer diametercorresponding to a diameter of the outer jacket.

The upper sieve wall and the upper partition both converge downwardlytoward the central opening in planes which are non-parallel, eachdefining a conical surface. If a “divergence angle” is drawn whichmeasures the degree of opening or “flare” of each conical surface, thenthe resulting divergence angle of the first cone forming the upper sievewall is greater than a divergence angle drawn for the second cone whichforms the upper partition.

Preferably, a divergence angle of a first cone forming an upper sievewall is an obtuse angle which is greater than 90° but less than 170°.The flare angle of the second cone which forms the upper partition canalso be greater than 90° but less than 170°, as long as the resultingdivergence angle is less than that of the first cone forming the uppersieve.

Cones of the upper and lower sieve walls can be provided having the sameobtuse angle.

In another version of the invention, the upper partition is again shapedas a cone with its vertex pointing down, the upper partition having acentral opening in its central part and its outer diameter correspondingto a diameter of the outer jacket. However, in this case, the uppersieve wall is essentially flat, rather than being shaped as a cone. Inother words, for this second version of the invention, the previouslydefined “divergence angle” is greater than 90° but less than or equal to180°, preferably equal to approximately 180°. All other features of thedesign are the same.

In both embodiments of the invention, the lower sieve wall can be shapedas a cone having its vertex directed downwards.

In one advantageous embodiment of the invention, the successivepartitions have alternately an outer diameter corresponding to adiameter of the outer jacket and smaller than a diameter of the outerjacket, whereas the partitions having an outer diameter corresponding tothe diameter of the outer jacket have a central opening in their centralpart.

In the most advantageous embodiment of the exchanger its upper partitioncan be provided with evenly distributed additional openings. Theseadditional openings are distributed on a locus of points defining onecircle or on many concentric circles.

The improved solution provided by the present invention is especiallyadvantageous because it essentially increases the effectiveness of heatexchange processes along the whole height of the pipe elements in theexchanger, as well as in the area of the upper sieve wall and thecombustion chamber.

Additional objects, features and advantages will be apparent in thewritten description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of the improved heat exchanger of theinvention with portions broken away for ease of illustration.

FIG. 2 is a side, cross sectional view of the heat exchanger of FIG. 1.

FIG. 3 is a side, cross sectional view, similar to FIG. 2, but showing asecond version of the invention with a flat upper sieve wall.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of a heat exchanger according to the presentinvention is shown in the drawings in which FIG. 1 shows the inside ofthe heat exchanger with portions thereof broken away for ease ofillustration and FIG. 2 shows the inside of the exchanger in thelongitudinal section.

This first version of a heat exchanger according to the principles ofthe present invention is built up of a vertical set of pipe elements 1,having generally rectangular cross-sections situated in a radiantarrangement, the respective opposing ends of said elements are connectedat an upper end to the upper sieve wall and at the opposing lower end toa lower sieve wall 3, as by using welding techniques. The upper andlower sieve walls 2,3 are preferably conically shaped. The upper andlower sieve walls 2, 3 can have the same shape with the first conehaving its vertex directed downwards.

With reference to FIG. 2 for the first version of the heat exchanger ofthe invention, it can be seen that the upper sieve wall 2 and the upperpartition 5 both converge downwardly toward central opening 8 in planeswhich are non-parallel, each defining a conical surface. If a“divergence angle”, i.e., the angles α and β in FIG. 2, are drawn whichmeasure the degree of opening or “flare” of each conical surface, thenthe resulting “divergence angle”α of the first cone forming the uppersieve wall 2 can be seen to be greater than a divergence angle β drawnfor the second cone which forms the upper partition 5.

Preferably, the divergence angle α of the first cone forming an uppersieve wall 2 is an obtuse angle which is greater than 90° but less than170°. The flare angle β of the second cone which forms the upperpartition 5 can also be greater than 90° but less than 170°, as long asthe resulting divergence angle is less than that of the first coneforming the upper sieve 2. The angle α can be, for example, in the rangefrom about 130 to 160°, while the angle β might be, for example in therange from about 120-150°, again so long as the angle α remains greaterthan the angle β.

In the particular embodiment of the invention illustrated, the angle αis approximately 155° and the angle β is approximately 145°.

Above the upper sieve wall 2, there is situated a cylindrical combustionchamber 4 made of metal sheet and connected by welding with said sievewall 2. Three horizontal partitions 5, 6, 7 are mounted across the setof pipe elements. The partitions 5, 6, 7 have a row of openingscorresponding to the section of pipe elements 1, which are going throughthese openings. The upper partition is shaped to form the second conehaving its vertex directed downwards. As has been explained, thedivergence angle β of this second cone is smaller than the divergenceangle α of the first cone, and equals approximately 130° in theexemplary case illustrated in the drawings. The middle partition 6 andthe lower partition 7 are shaped as flat discs. A relatively largecentral opening 8 is located in the middle part of the upper partition 5and of the lower partition 7.

A package made up of a set of the pipe elements 1, the sieve walls 2, 3,the partitions 5, 6, 7, and the cylindrical combustion chamber 4 isenclosed in the outside jacket 9 shaped as a truncated cone with itsdiameter increasing upwards. The upper partition 5 and the lowerpartition 7 have their outer diameters corresponding to the innerdiameters of the outer jacket 9, whereas the middle partition 6 has itsouter diameter smaller than the inner diameter of the outer jacket 9 atthe height of said partition.

The exchanger is closed from the upper side by a cover 10 provided witha gas inlet stub pipe, an opening for a burner with a valve-ventilationsystem, as well as other conventional elements essential for assemblingthe fittings and housing of a boiler comprising said heat exchanger.

The lower sieve wall 3 is connected permanently to the inner jacket 9 bywelding in the indicated joint locations. The cover 10 is connectedseparately by means of screws with the outer jacket and with thecombustion chamber 4. The water inlet stub pipe 11 (shown in FIG. 1) andwater outlet stub pipe 12 are situated respectively in the lower sideand the upper side of the outer jacket 9, and the lower tank 13 islocated under the lower sieve wall 3. The condensate outlet stub pipe 14and the exhaust fumes outlet stub pipe 15 are located in this lower tank13. In the particularly preferred embodiment of the exchanger of theinvention illustrated in FIG. 1, the upper partition 5 has a series ofadditional openings 16 evenly arranged in a circle between the set ofpipe elements 1.

The exchanger is designed to burn natural gas and propane in order togenerate the heat needed to warm up water used in central heatingsystems. Gas is burnt in the upper part of the exchanger in thecombustion chamber 4, and then combustion fumes flow by the pipeelements 1 vertically downwards to transfer heat into the water beingheated. The water is circulating in the outer jacket 9 between the waterinlet 11 and the water outlet 12. Flowing down combustion fumes arecooled below their dew-point, and are gathered in the lower tank 13.From here they flow outside together with the rest of the condensatethrough the condensate outlet 14 and the combustion fumes outlet 15.

The heated water flows outside the pipe elements 1 in counter flow inrelation to the flowing combustion fumes. In this way, water isintroduced by the water inlet stub pipe 11 situated in the lower part ofthe exchanger, and flows upwards, washing the pipe elements 1 and thecombustion chamber 4. It is then carried out from the exchanger by meansof the water outlet stub pipe 12 located in the upper part of theexchanger.

The pipe elements 1 and the combustion chamber 4 are suitably washed,said washing being forced by the provided set of partitions. The flow isdirected by the central opening 8 made in the lower partition 7 to thecentral part of the exchanger and then to walls of the outer jacket 9around the outer edges of the middle partition 6 and afterwards oncemore to the middle point from which a flow is directed through thecentral opening 8 made in the upper partition 5 to the central point ofthe upper sieve wall 2. In this way, this wall, together with thecombustion chamber, is washed evenly in all directions. Any water whichhappens to be stopped in dead areas below the upper partition 5 flowsthrough the additional openings (16 in FIG. 1) provided in thispartition 5.

In the exemplary embodiment illustrated in FIGS. 1 and 2 of thedrawings, the exchanger comprises 20 pipe elements. It's height is 600mm, the diameter of its upper part being approximately 350 mm, and thediameter in the lower part as well as the diameter of the combustionchamber being approximately 300 mm. A exchanger constructed as describedensures a maximum outlet water temperature of approximately 90° C.

In other embodiments of the first described version of the invention theheat exchanger having an upper cone sieve wall and an upper conepartition may comprise a different number of remaining partitions havingan alternately different outer diameter and being alternately providedwith great central openings. In an advantageous embodiment the lowersieve wall is a cone wall shaped exactly in the same way as the cone ofthe upper sieve wall, but in other embodiments of the exchanger thesecones have different divergence angles and the lower sieve wall may beflat or may be shaped in another way. Sections and arrangement of thepipe elements may differ as well in some versions of the exchanger.

FIG. 3 shows another version of the heat exchanger of the invention. Itwill be evident that all of the design features of this version of theheat exchanger are basically identical to those of the first versionshown in FIGS. 1 and 2 with the exception of the upper sieve wall (2 inFIG. 3). In this case, the upper sieve wall 2 is a planar or near planarsurface as viewed from the side. In other words, the upper sieve wall 2is basically flat, rather than being conically shaped. In terms of thepreviously defined “divergence angle” described with respect to FIG. 2,the angle formed by the upper sieve wall 2 in FIG. 3 is greater than90°, but less than or equal to 180°, preferably equal to approximately180°. The angle β, which represents the divergence angle of the upperpartition 5, is not particularly critical, and can be in the range, forexample, from about 120°-160°, preferably about 130°-150°. In theparticular example illustrated in FIG. 3, the angle β, which representsthe divergence angle of the upper partition 5, is approximately 145°.

In the case of the first version of the invention having a conicallyshaped upper sieve wall, the shapes of the upper and lower sieve walls2, 3, as well as shapes of the corresponding central openings in thepartitions, produce an unusually advantageous water circulation in theexchanger, increasing its heat exchange efficiency. The improvedefficiency is due in part to the increased flow speed of the liquidwashing the upper sieve wall and the combustion chamber in the area ofthe combustion chamber as a result of the newly designed shape of theupper sieve wall 2 and the upper partition 5. The improved efficiency isalso particularly the result of the difference between the divergence ofthe first cone creating the upper sieve wall and the second conecreating the upper partition. The particular choice of angles for thesesurfaces results in the advantageous influence of increasing the heatexchange efficiency in the region of the combustion chamber. Theadditional openings 16 in the upper partition 5 prevent creation of socalled “dead zones” under the partition without any movement of water byallowing a controlled flow. This is accomplished by means of a liquidleakage between areas under the partition and above the partition in thedetermined places.

In the case of the second version of the invention with the essentiallyflat upper sieve wall and conically shaped upper partition, the watercirculation may not equal that of the first version of the invention.However, the second version with its flat upper sieve wall is a muchmore economical manufacturing solution because the manufacturing processis extremely simple, especially where the flat or conically shaped sievewalls are desired to be made of relatively thick materials. Thus, insome senses, the second version of the invention provides the bestbalance between cost and efficiency in a heat exchanger of this type.

Another factor to be considered in comparing the two designs is the factthat the first version of the heat exchanger with the conically shapedupper sieve wall the water flow has laminar characteristics. In somesituations where the water being used has a high mineral content, thischaracteristic could possibly lead to limestone build-up. In the case ofthe second heat exchanger with the flat upper sieve wall, the water flowbetween the sieve wall and the upper partition is turbulent and anypossibility of limestone build-up is reduced because of the continuousmixing of the water. In other words, the layer of water which isdirectly below the upper sieve wall is not overheated. These factors mayextend the useful life of the heat exchanger in the particular situationoutlined above. This characteristic of turbulent water flow does notcreate the optimal heat exchange situation created by the first versionof the invention, but the turbulent flow of the water helps to make thedifference in the efficiency of the two designs less significant.

While the invention has been shown in only two of its forms, it is notthus limited but is susceptible to various changes and modificationswithout departing from the spirit thereof.

1. A heat exchanger, comprising: an outer jacket; an inner set ofvertical pipe elements having opposing ends, the pipe elements beingfastened at their respective opposing ends between an upper and a lowersieve wall; a gas combustion chamber located above the upper sieve wall;a plurality of partitions mounted within the outer jacket in crosswiserelationship to the vertical pipe elements, the partitions havingopenings for receiving the pipe elements; wherein the heat exchanger isalso provided with liquid, gas and exhaust fumes inlet and outlet stubpipes; the heat exchanger also being further characterized in that theouter jacket is conically shaped with a diameter which increases in anupward direction; and wherein the upper partition which is situatedbelow the upper sieve wall is shaped as a cone having a vertex whichpoints downwardly, the upper partition having a central opening providedin a central region thereof, and an outer diameter which corresponds toa diameter of the outer jacket.
 2. The heat exchanger of claim 1,wherein the upper sieve wall forms a planar or near planar surface, asviewed from the side, while the upper partition converges downwardlytoward the central opening in a plane which is non-parallel to that ofthe upper sieve wall, thereby defining a conical surface of a cone,whereby if a divergence angle is drawn which measures a degree ofopening or flare of the conical surface of the upper partition, then theplanar surface of the upper sieve wall will form a greater divergenceangle than the divergence angle drawn for the cone which forms the upperpartition.
 3. The heat exchanger of claim 2, wherein the divergenceangle of the upper sieve wall is greater than 90° but less than or equalto 180°.
 4. The heat exchanger of claim 3, wherein the divergence angleof the upper sieve wall is approximately 180°.
 5. The heat exchanger ofclaim 2, wherein the divergence angle of the upper partition is in therange from about 120°-160°.
 6. The heat exchanger of claim 1, whereinthe lower sieve wall, like the upper partition, is also shaped as a conehaving its vertex directed downwards.
 7. The heat exchanger of claim 5,wherein the cones of the upper partition and lower sieve wall each havethe same divergency angle.
 8. The heat exchanger of claim 1, whereinsuccessive partitions located within the outer jacket have alternatelyan outer diameter corresponding to the diameter of the outer jacket andthen smaller than the diameter of the outer jacket, whereas thepartitions having an outer diameter corresponding a diameter of theouter jacket also have a central opening in to central region thereof.9. The heat exchanger of claim 1, wherein the upper partition isprovided with evenly distributed additional openings in the conicalsurface thereof.
 10. The heat exchanger of claim 8, wherein theadditional openings are located in a locus of points which define onecircle or a plurality of concentric circles.